A COMPARISON OF PT OVERLAYERS ON ALPHA-AL2O3(0001), ZNO(0001)ZN, AND ZNO(0001)O

被引:63
作者
ROBERTS, S
GORTE, RJ
机构
[1] Department of Chemical Engineering, University of Pennsylvania, Philadelphia
关键词
D O I
10.1063/1.459653
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The growth of Pt films on ZnO(0001)Zn and ZnO(0001)O and their adsorption properties for CO have been studied and compared to results obtained for Pt on α-Al2O3(0001). Samples were prepared by vapor deposition of Pt onto flat substrates in ultra high vacuum, and metal coverages were measured using a quartz-crystal, film thickness monitor. On both ZnO surfaces, Auger electron spectroscopy (AES) and transmission electron microscopy (TEM) indicate that Pt grows in as a 2D film at 300 K, in contrast to results for Pt on α-Al2O3(0001) where 3D particles are formed under these conditions. Furthermore, transmission electron diffraction (TED) showed that the Pt grew as an ordered overlayer on the ZnO crystals. Heating the Pt/ZnO surfaces resulted in the formation of Pt particles starting at ∼650 K, but the Pt particles were still oriented with the ZnO. On both ZnO surfaces, temperature programmed desorption (TPD) curves for CO from high Pt coverages (> one monolayer) and from Pt particles formed by heating thinner films were identical to TPD curves for CO from Pt on α-Al 2O3(0001). The main desorption features were observed at 400 and 510 K and are interpreted as being due to different site geometries on the Pt by comparison to results from Pt single crystals. However, for Pt at submonolayer coverages prior to particle formation, the TPD curves for CO from Pt on ZnO(0001)Zn were shifted down in temperature by ∼60 K compared to results for Pt on ZnO(0001̄)O. These results are interpreted as indicating a chemical interaction between Pt and the Zn+2 ions which are in direct contact. © 1990 American Institute of Physics.
引用
收藏
页码:5337 / 5344
页数:8
相关论文
共 54 条
[1]   THE DESORPTION OF CO FROM SMALL PT PARTICLES ON AL2O3 [J].
ALTMAN, EI ;
GORTE, RJ .
SURFACE SCIENCE, 1986, 172 (01) :71-80
[2]   A STUDY OF SMALL PT PARTICLES ON AMORPHOUS AL2O3 AND ALPHA-AL2O3[0001] SUBSTRATES USING TPD OF CO AND H21 [J].
ALTMAN, EI ;
GORTE, RJ .
JOURNAL OF CATALYSIS, 1988, 110 (01) :191-196
[3]   A COMPARISON OF THE DESORPTION OF CO FROM PT AND RH PARTICLES ON ALPHA-AL2O3(0001) [J].
ALTMAN, EI ;
GORTE, RJ .
SURFACE SCIENCE, 1988, 195 (03) :392-402
[4]  
ATLMAN EI, 1989, SURF SCI, V216, P386
[5]   ELECTRON-MICROSCOPY OF SUPPORTED METAL PARTICLES .1. BEHAVIOR OF PT ON TITANIUM-OXIDE, ALUMINUM-OXIDE, SILICON-OXIDE, AND CARBON [J].
BAKER, RTK ;
PRESTRIDGE, EB ;
GARTEN, RL .
JOURNAL OF CATALYSIS, 1979, 56 (03) :390-406
[6]   SUPPORT AND MORPHOLOGICAL EFFECTS IN THE SYNTHESIS OF METHANOL OVER CU/ZNO, CU/ZRO2 AND CU/SIO2 CATALYSTS [J].
BARTLEY, GJJ ;
BURCH, R .
APPLIED CATALYSIS, 1988, 43 (01) :141-153
[7]   METAL SUPPORT INTERACTIONS ON RH AND PT/TIO2 MODEL CATALYSTS [J].
BELTON, DN ;
SUN, YM ;
WHITE, JM .
JOURNAL OF PHYSICAL CHEMISTRY, 1984, 88 (22) :5172-5176
[8]   IR STUDY OF THE CO ADSORPTION ON PT/ZNO SAMPLES - EVIDENCE FOR A PTZN PHASE FORMATION IN THE SMSI STATE [J].
BOCCUZZI, F ;
CHIORINO, A ;
GHIOTTI, G .
SURFACE SCIENCE, 1989, 209 (1-2) :77-88
[9]   A COMPARISON OF RANEY COPPER-ZINC AND COPRECIPITATED COPPER-ZINC-ALUMINUM OXIDE METHANOL SYNTHESES CATALYSTS [J].
BRIDGEWATER, AJ ;
WAINWRIGHT, MS ;
YOUNG, DJ .
APPLIED CATALYSIS, 1986, 28 (1-2) :241-253
[10]   CU/ZNO(0001-BAR) AND ZNOX/CU(111) - MODEL CATALYSTS FOR METHANOL SYNTHESIS [J].
CAMPBELL, CT ;
DAUBE, KA ;
WHITE, JM .
SURFACE SCIENCE, 1987, 182 (03) :458-476